15 research outputs found
Two Moving-Angled 1-Branes with Electric Fields in a Partially Compact Spacetime
In this article we consider two -branes at angle in the presence of the
background electric fields, in a partially compact spacetime. The branes have
motions along a common direction that is perpendicular to both of them. Using
the boundary state formalism, we calculate their interaction amplitude. Some
special cases of this interaction will be studied in detail.Comment: 10 pages, no figure, Late
Self-Dual Chern-Simons Solitons in (2+1)-Dimensional Einstein Gravity
We consider here a generalization of the Abelian Higgs model in curved space,
by adding a Chern--Simons term. The static equations are self-dual provided we
choose a suitable potential. The solutions give a self-dual
Maxwell--Chern--Simons soliton that possesses a mass and a spin
N=2 structures on solvable Lie algebras: the c=9 classification
Let G be a finite-dimensional Lie algebra (not necessarily semisimple). It is
known that if G is self-dual (that is, if it possesses an invariant metric)
then there is a canonical N=1 superconformal algebra associated to its N=1
affinization---that is, it admits an N=1 (affine) Sugawara construction. Under
certain additional hypotheses, this N=1 structure admits an N=2 extension. If
this is the case, G is said to possess an N=2 structure. It is also known that
an N=2 structure on a self-dual Lie algebra G is equivalent to a vector space
decomposition G = G_+ \oplus G_- where G_\pm are isotropic Lie subalgebras. In
other words, N=2 structures on G are in one-to-one correspondence with Manin
triples (G,G_+,G_-). In this paper we exploit this correspondence to obtain a
classification of the c=9 N=2 structures on self-dual solvable Lie algebras. In
the process we also give some simple proofs for a variety of Lie algebraic
results concerning self-dual Lie algebras admitting symplectic or K\"ahler
structures.Comment: 49 pages in 2 columns (=25 physical pages), (uufiles-gz-9)'d .dvi
file (uses AMSFonts 2.1+). Revision: Added 1 reference, corrected typos,
added some more materia
Quantum Kinks: Solitons at Strong Coupling
We examine solitons in theories with heavy fermions. These ``quantum''
solitons differ dramatically from semi-classical (perturbative) solitons
because fermion loop effects are important when the Yukawa coupling is strong.
We focus on kinks in a --dimensional theory coupled to
fermions; a large- expansion is employed to treat the Yukawa coupling
nonperturbatively. A local expression for the fermion vacuum energy is derived
using the WKB approximation for the Dirac eigenvalues. We find that fermion
loop corrections increase the energy of the kink and (for large ) decrease
its size. For large , the energy of the quantum kink is proportional to ,
and its size scales as , unlike the classical kink; we argue that these
features are generic to quantum solitons in theories with strong Yukawa
couplings. We also discuss the possible instability of fermions to solitons.Comment: 21 pp. + 2 figs., phyzzx, JHU-TIPAC-92001
The Initial-Final Mass Relation among White Dwarfs in Wide Binaries
We present the initial-final mass relation derived from 10 white dwarfs in
wide binaries that consist of a main sequence star and a white dwarf. The
temperature and gravity of each white dwarf was measured by fitting theoretical
model atmospheres to the observed spectrum using a fitting
algorithm. The cooling time and mass was obtained using theoretical cooling
tracks. The total age of each binary was estimated from the chromospheric
activity of its main sequence component to an uncertainty of about 0.17 dex in
log \textit{t} The difference between the total age and white dwarf cooling
time is taken as the main sequence lifetime of each white dwarf. The initial
mass of each white dwarf was then determined using stellar evolution tracks
with a corresponding metallicity derived from spectra of their main sequence
companions, thus yielding the initial-final mass relation. Most of the initial
masses of the white dwarf components are between 1 - 2 M. Our results
suggest a correlation between the metallicity of a white dwarf's progenitor and
the amount of post-main-sequence mass loss it experiences - at least among
progenitors with masses in the range of 1 - 2 M. A comparison of our
observations to theoretical models suggests that low mass stars preferentially
lose mass on the red giant branch.Comment: 28 pages, 8 figures, accepted for publication in Ap
eta' to eta pi pi Decay as a Probe of a Possible Lowest-Lying Scalar Nonet
We study the eta' to eta pi pi decay within an effective chiral Lagrangian
approach in which the lowest lying scalar meson candidates sigma(560) and
kappa(900) together with the f0(980) and a0(980) are combined into a possible
nonet. We show that there exists a unique choice of the free parameters of this
model which, in addition to fitting the pi pi and pi K scattering amplitudes,
well describes the experimental measurements for the partial decay width of
eta' to eta pi pi and the energy dependence of this decay. As a by-product, we
estimate the a0(980) width to be 70 MeV, in agreement with a new experimental
analysis.Comment: 25 pages, 11 figure